Question

I have a wep app that uses both knockout.js and require.js libraries. Let’s say that I have a ‘User’ model and a ‘Customer’ model. I want the Customer model to inherit from User, so I now have the following code:

User.js

define(['knockout'], function(ko){

    return function User(){

        var self = this;
        self.id = ko.observable();
        self.firstname = ko.observable();
        self.name = ko.observable();
    };
});

Customer.js

define(['knockout', 'model/user'], function(ko, User){

    return function Customer(){

        var self = this;
        self.address = ko.observable();
    };
    Customer.prototype = new User();
});

When I create a Customer with the following code:

var c = new Customer();
c.id(1);
c.firstname("John");
c.name("Doe");
c.address("Unknown");

Then I get the following error in the Chrome console:

Uncaught TypeError: Object #<Customer> has no method 'id' 

When I set only the address property, I don’t see this error so I’m assuming that there is something wrong with the inheritance. Any help is very welcome.

Answer 1

The following line will never be executed because you use return before:

Customer.prototype = new User();

Update customer.js to this:

define(['knockout', 'model/user'], function(ko, User){

    function Customer (){

        var self = this;
        self.address = ko.observable();
    };
    Customer.prototype = new User();
    return Customer;
});